Mechanical relaxation near glass transition studied by various methods

Viscosity in pure shear deformation mode was measured for various glasses. The temperature dependence of viscosity was of hydrodynamic (Vogel–Tammann–Fulcher) type and of the hopping (Arrhenius) type above and below the glass transition temperature. Double Arrhenius dependence was seen in glasses containing molecular chains. Internal friction was measured near and above the glass transition for metallic and polymer glasses. The viscoelastic relaxation was observed and the result was analyzed by adopting the Maxwell model and the Maxwell relation. In the relaxation a correlation between the pre-exponential factor and the activation energy (compensation effect) was seen. Ultrasound and Brillouin scattering experiments were performed for a polymer glass. Relaxation was seen near the glass transition in the sound velocity and sound attenuation. The activation energy values for the relaxation obtained by various experiments were compared by adopting the idea of potential energy landscape.